In prior art notching machines it has been attempted to achieve that a shaping pulley is installed and removed easily and expeditiously in order to obtain, through a manual operation, a replacement of a pulley by another one with different diameter, with a result that differently sized recesses can be performed.
Among others, U.S. Pat. No. 5,357,714 granted to Landhuis on Oct. 25, 1994 discloses an apparatus for grinding recesses, wherein a shaping pulley has a through shaft with races for ball bearings. The one end of the through shaft of the shaping pulley is inserted in a hole, and the opposite end of the shaft is pushed into a fork provided with stop means, the hole and the fork being performed in side walls of the apparatus respectively. In the side walls, internally, there are pivotally put two pairs of ball bearings, respectively, which are designed to engage said races in the shaft of the shaping pulley. The arrangement of this shaping pulley on the grinding machine requires accurately machined surfaces for the coupling of the races in the shaft with the pairs of ball bearings. Further, a great number of components is required.
U.S. Pat. No. 5,437,570, also granted to Landhuis on Aug. 1, 1995 discloses an apparatus for grinding recesses, wherein a shaping pulley has a shaft section on both its sides. Each shaft section is provided with a coaxial bearing element that is designed to be received and locked into tapered housings internally formed in respective side walls of the apparatus. One should appreciate that the above mentioned disposition requires that each shaping pulley is provided with a couple of ball bearings being of an internal diameter corresponding to the diameter of the shaft sections.
Furthermore, in an apparatus for grinding recesses or notching machine with ready replacement of its shaping pulley according to the previous patent application PCT No. 01/00469 of the same inventor, a supporting device for a shaping pulley, which has shaft sections in its opposite ends, is provided with rest bushings housing a rolling bearing for receiving a respective shaft section of said shaft sections of the shaping pulley, rest bushings that are mounted on a movable assembly connected to the frame of the notching machine by means of a clamping element to the frame of the apparatus.
In the prior art notching machines the supporting device for a shaping pulley is mounted on open rolling bearings, i.e. without any protection. Therefore, these open rolling bearings, which are further subjected to the vibrations generated at high speeds as well as to the contaminating action of chips and wastes due to the wear of the grinding belt in its operation, tend to be damaged easily and to have a short life, with a consequence of rise in costs and in waste of time for an operator of the machine. As a result, each rolling bearing on the ends of the shaping pulling is affected in a particularly considerable way, with equal grinding belt and same number of revolutions per minute of the driving pulley, when the idle shaping pulley is of a very small diameter to grind corresponding recesses, the rotation speed of the shaping pulley increasing in inverse proportion with a decrease of its diameter.
An object of the present invention is to permit the location of the shaping pulley in a notching machine without any risk of blocking due to a failure of its support rolling bearings.